# Pinewood Derby Time!

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#### OKTurbo

##### Well-Known Member
TRF Supporter
Looks like I'll have to move the rockets off the building table for a while. It's Pinewood Derby time! My 8 yr old, Philip, recieved his PWD kit monday night at our annual "Blue&Gold" Cub Scout Pack Meeting. Time to start carving....once the "project manager" decides on a design.

We've gotten pretty good at this. My 12 year old, Timothy, has moved up to Boy Scouts, but we have 5 cars that he's built over the years. (from TigerCubs thru Webelos II). Philip is now a Bear Scout...awarded his Bear rank at monday's meeting, so this will be his 3rd PWD car. The building of Philip's Positron rocket was one of his achievements to Bear rank BTW.

My father (Papa to the boys) and I put a new rubbed tung oil finish on the track over the Christmas holidays this year. So we are ready to go!

Making memories....thought I would share...

John

#### cls

##### Well-Known Member
we're doing a pinewood derby in the YMCA Adventure Guides this year. we don't know anything about it so I would be interested to hear some of your "secrets" to make it go.

#### WiK

Could someone fill me in here. What is a pinewood derby?!?

I dont think we have them over here.

Phil

#### OKTurbo

##### Well-Known Member
TRF Supporter
If you do a Google search for PineWood Derby you'll be surprised how much info is out there. For our Cub Scouts we try and keep everyone to the official BSA rules. In other words...no knife edge wheels...or funny wheel bearings. They must be built using the parts in the box and follow the official dimensions for height x length x width plus max weight.

The biggest tips are to take all the casting flash off the wheel's running surface. Polish the "nails" / axles to get any imperfections off them and load up on graphite or teflon dry lube. Make sure all the wheels are lined up good and straight. Some guys try to get it so that only 2 wheels...one in front and the opposite side on the rear are touching (less rolling friction). Add weight to get exactly 5 oz...take trim weights the night of the race for the official weigh-in so you can get 5 oz on the official scale.

Weight placement kinda depends on what track your club has. The official BSA track slopes at first then goes to a flat section for the final run to the finish line. If your track is like this....put the weight as far back as you can. This puts the CG higher up on the ramp when the car is on the starting line, giving you a longer run for acceleration.

If you have a flat, ramp style track that slopes evenly all the way from start to finish, weight placement really doesn't matter.

The point of the whole thing is to let the boys have fun building a car and working with their dad (or mom / grandparent / etc) on a project. I tend to let my boys do the lion's share of the building. The cars look good, but you can tell they were built by a kid. I've found that aerodynamics don't really have much to do with it...it's mostly in the wheel alignment and axle friction. We've had some pretty funky designs (like a hot-dog car) that have won.

Just remember...have fun...spend some time with the kids and be sure to have a talk with them before you start about winning/losing/sportsmanship. Don't allow a group of kids to cheer just one car on. Cheer for everyone. Shake hands after each race. It's easy for kids to get their feelings hurt. We even give out a "flat tire" award for the boy that loses all his races.

It's not about the winning and losing. It's about the memories you fill these kid's head with.

Have Fun,
John

#### powderburner

##### Well-Known Member
Originally posted by WiK
Could someone fill me in here. What is a pinewood derby?!?

It is a contest for children to teach a few craft and mechanical skills, and to encourage development of a little inventiveness and creativity.

#### OKTurbo

##### Well-Known Member
TRF Supporter
We tried the rocket derby a couple of years ago. We actually did it for a few years. It was fun, but not nearly as popular as the PWD. The problem with the BSA rocket derby is there is so much prep that has to be done before each race. It made for some late nights with the little guys. We didn't like keeping the kids up 'til 10:00 on a school night. Plus all the holes in the action give the boys too much time to become disinterested in what was going on.

The BSA (Boy Scouts of America) Rocket Derby uses hollow balsa wood rockets with plastic fins and a hook/carrier on top. A plastic propeller and rubber bands are used to propel the rockets. Before each heat the boys have to wind up the rubber band...often breaking it while trying to get the maximum turns in it...this requires them to reload the rubber motor...etc...etc...
When you get the racers ready, the rockets are loaded up on wires that you string across the room. We had a starting device that held the rockets and kept the propellers from spinning, but I can't even remember exactly what it looked like.

It takes a lot of patience to run a Rocket Derby.

John

##### Well-Known Member
Here are the cars